1. Field of the Invention
The present invention relates to pipe couplings and, more particularly, to a female coupling member of a pipe coupling suitable for handling a high-pressure fluid.
2. Description of the Related Arts
A pipe coupling is generally arranged such that a male coupling member is inserted into a female coupling member, and in this state, the two coupling members are coupled and locked in coupled relation. As a common means for locking the male and female coupling members in coupled relation, balls are radially displaceably provided in a male coupling member receiving portion of the female coupling member. When the male coupling member is inserted into the male coupling member receiving portion, the balls are displaced radially inwardly to engage into a ball receiving recess provided on the outer peripheral surface of the male coupling member (see Japanese Patent Application No. 2003-133618).
These balls, however, need to be strongly pressed against the ball receiving recess of the male coupling member when the pipe coupling handles a high-pressure fluid, for example. In such a case, the ball receiving recess is likely to be dented by the balls and may become incapable of satisfactorily performing the desired locking function after use for a certain period of time.
Meanwhile, a collet chuck type locking means is used occasionally. This locking means has a plurality of locking members that are provided at a predetermined regular interval around the male coupling member receiving portion of the female coupling member and that extend in a direction in which the male coupling member is received in the male coupling member receiving portion. The locking members are pivotably supported in a lever fashion. Latch portions provided at the forward ends of the locking members are engaged or disengaged with respect to a locking recess provided on the outer peripheral surface of the male coupling member (see U.S. Pat. No. 2,888,278).
The latch portions of the locking members cause a reduced degree of denting compared to that of the above-described balls. However, the locking members are provided at a forward end portion of the male coupling member receiving portion of the female coupling member, and are adapted to lock the male coupling member by receiving it into a space defined by the locking members having their latch portions expanded radially outwardly and then displacing the latch portions radially inwardly into engagement with the locking recess. Therefore, the male coupling member and the female coupling member cannot always be accurately centered when they are locked by latching. As a result, the male coupling member and the female coupling member may fail to be connected properly.